"How to Wowhead"
open up the html file in any texteditor (some works better btw) and just use Find&Replace feature.
Quests:
Find: hxxp://www.joanaguides.com/81/2ia1749390.php?
Replace: hxxp://www.wowhead.com/?quest=
NPCs:
Find: hxxp://www.joanaguides.com/81/2jam2482651.php?
Replace: hxxp://www.wowhead.com/?npc=
Items:
Find: hxxp://www.joanaguides.com/81/2la1212299.php?
Replace: hxxp://www.wowhead.com/?item=
In this way you "should" replace all allakhazam links in the guide with wowhead one.
Also, in this way you get rid of all links pointing to joanaguides.com (so he/she, doens't know you're using his/her guide).
There're some little issue btw...some links could not be working.
For example, Thottbot uses different IDs from allakhazam/wowhead, so it's a little more difficult for them, also, links to video need another way to be replaced.
Other than that, this should be a working method.
Also, there're some spot in the guide, without link to Allakhazam (or without link to Thottbot).
Personally, i'd get rid of any links to joanaguides.com, but...it's not so simple

First, all the joanaguides.com link should be replaced by their corrispective Allakhazam/Thottbot/videos links....then, these should be replaced by the one you prefer.
mrmr
P.S.
regex rules